Stove



A135129, 141 H E MILLS ETAL 2,240,340

STOVE Filerd Aug. 2l, 1936 Patented Apr. 29, 1941 STOVE Herbert E. Mills and Ervern F. Dupuis, Detroit, Mich., assignors to Borg-Warner Corporation, a corporation of Illinois Application August 21, 1936, Serial No. 97,124

2 Claims.

This invention relates to stoves and has particular reference to an improvement in a ther mostatic control therefor.

It is the principal object of the invention to provide a novel form of thermostatic control whereby the operator can tell when the oven is on and when it is at the desired temperature.

Another object of the invention is to provide a novel form of thermostatic control whereby a closing of one circuit is revealed by the illumination of one colored lamp, and a closing of another circuit is revealed by the simultaneous illumination of another colored lamp.

Another object of the invention is to provide a novel form of thermostatic control whereby a closing of one circuit is revealed by the illumination* of one colored lamp, and a closing of another circuit is revealed by the simultaneous' illumination of another colored lamp, said second named lamp being adapted to flicker on and off when the oven is at its desired temperature.

Another object of the invention is to provide a novel form of thermostatic control particularly adapted to be used in connection with stoves of the domestic type.

Another object of the invention is to provide a novel form of thermostatic control which is inexpensively constructed and operated and particularly adapted for revealing the conditions within the oven compartment by means of lamps of small wattage.

Another object of the invention is to provide a thermostatic control which is especially adapted to utilize the energy of electricity and the energy of heat for acquiring the desired series of results apparatus at the lowest possible cost.

Another object of the invention is to provide a thermostatic control which consists of a necessary series of circuits and lamps, skillfully and novelly hooked up, which will indicate, when a switch is turned on, that the oven is on, and which will indicate, also, that the oven has reached its desired temperature.

Other objects of the invention will be apparent from a reference to the following specification taken in conjunction with the accompanying drawing of which there is one sheet, and in which:

Figure l is a perspective view of a portion of a stove embodying the invention;

Figure 2 is a front elevational view of the control shown partly in section; and

Figure 3 is an elevational perspective view of the control, greatly enlarged, and shown in section.

Fig. 4 is a circuit diagram of the control in its open or oi position.

Figure l shows a stove IIJ with a thermostatic control, generally indicated at I2, and disposed on panel I5. Thermostat I2 comprises a translucent dial I6 rigidly mounted to panel I5 and having impressed thereon numbers representing selective temperatures. Acting as a breakage preventative for dial I6 is a metal frame I1 which covers the periphery of said dial but does not obscure the numerals thereon. Dial IB is provided with a centrally located cavity I8. A switch I9, adapted for rotative manipulation, extends forwardly of dial I6 for manual selection of the oven heat desired; this switch is appropriately shaped to form an indicator of familiar appearance; it is provided with an inner bore 20 adapted for xed engagement therein of a plunger 22 which is iixedly screwed to a bolt 23 and resiliently backed up by a spring 24, said spring telescoping bolt 23 behind plunger 22.v

Bolt 2'3 extends rearwardly through cavity I8 and is bifurcated at its rearward end for engagement with a transverse pin 25 which is rigidly inserted into and through a portion of a rod 25. Rod 25' is threaded at its rearward end and screwed into an internal threaded portion of a metal retainer 26. Rod 25', being limited in its rearward motion by shoulder 21 and by a limitedy number of threads in retainer 28, and being connected to bolt 23 by pin 25, prevents switch I9 from being turned more than' a little less than a full turn. It can be seen that adjustments can be made to prevent excessive turning of switch I9 either by adjusting rod 25' or by adjusting plunger 22 on bolt 23. Between the bifurcated end of the bolt 23 and the spring 2l is a plurality of metal discs 28 which are rigidly connected to bolt 23 and from one of which forwardly projects a lug 29 which coactively extends into a small bore 3u in switch I3; this is another means for insuring rotative movement of bolt 23 when switch I9 is manually operated.

Disposed behind and connected to discs 28 is a metal cam 3|. This cam at its lower end projects substantially rearwardly and prevents forward motion of a spring-pressed non-conducting plunger 32 which is adapted for horizontal sliding motion in the control housing. Disposed behind and having its upper portion pressing against plunger 32 at 33 is a copper spring 34 the lower end of which is connected to the inner Wall of the control housing forming a terminal, generally indicated at 35, to which neutral wire 36 is connected. A neutral conductor 3l is secured to the control housing by a conducting screw I5 which extends into and through the housing to within a short distance of spring 34. Forward motion of plunger 22 allows spring 24 to contact screw 35 at 55.

A green lamp 45 and a red lamp 4| are adapted to be resiliently contacted from below by conductor 51 at 42 and 42' respectively, and to be screwed into metal brackets 45 and 43' respectively, at 44 and 44' respectively. Lamps 45 and 4| are preferably 'I watt bulbs and disposed behind translucent dial I5.

`45 and 45 represent, generally, the terminals to which a 220 v. source is connected. 41 and 45 represent, generally, the terminals to which a heating element is connected. The terminals 45 and 45 project electrically through the control housing and terminate at the inner side thereof at contacts 45' and 45' (the latter not shown). The terminals 41 and 45 project electrically through the control housing and terminate at the inner side thereof at contacts 41 and 4l' (the latter not shown) Metal conducting bracket 45 forms the electrical continuity between neutral conductors 35 and 51, green lamp 45, and terminal 45; metal conducting bracket 45 forms the electrical continuity between neutral conductors I5 and 21, red lamp 4|, terminal 45, a switch 55, and terminal 45. Disposed behind and level with terminals 45 and 41' is a continuous metal contactor 45 which is capable of -being sprung forwardly (when switch |5 is operated) so that the upper and lower portions thereof contact 45' and 41 respectively: disposed similarly with relation to terminals 45T and 45' is a continuous metal contactor 55 (not shown) which springs forwardly', the upper and lower portions of which contact 45' and 45', respectively, when switch I5 ls turned on. Insulation lies between and behind contactors 45 and `55, since these contactors are used for closing the circuit containing the heating element and the circuit containing the red lamp. This insulation is comprised of a Bake lite block 5| (not shown) plvoted at the center for slight movementy in a horizontal plane for automatic adjustment of the pressure between contacts 45, 45', and 41', and between contacts 55. 45'. and 45'` A thin L shaped bar 52 extends rearwardly and horizontally from the pivotal point of block 5|, and then downwardly to contact with a spring 55 at 55. Spring 53 is bifurcated at its lower end and engageably fitted to a bolt 54. The rear end of bolt 54 serves as a stop while switch I5 is in its off position, said stop being limited in its rearward motion by the rear cover plate 55 of the control housing; the

forward end of the bolt 54 is rigidly fastened to the lower end of a spring 55. A center portion 51 of spring 55 is cut out so that bar 52 can extend therethrough, a portion 55 of spring 55 is cut out above 51 so that rod 25' can extend therethrough, and a portion 55 of spring 55 is cut out above 55 so that a bolt 55 can pass therethrough. y

The rearward end of bolt 55 is threaded and engageable with a threaded portion of plate 55 at 5|; the forward end o! bolt 55 is flanged at 55 so as to retain atelescopical coil spring 52 therebehind and ln front of spring 55. This coil spring 52 is sufficiently strong enough to keep the top portion of spring 55 stationary and in place regardless of the conditions in the control unit. It will be seen, therefore, but explained subsequently, that forward motion of rod 25' will allow rigidly connected to the lower portion of spring 55 by means of bolt 54, will allow the lower portion of spring 53 to be sprung forwardly; this forward motion of the lower portion of spring 55 is adapted to cause the upper portion of spring 55 to be sprung rearwardly; and, since v the upper portion of spring 53 is rigidly connected to bar 52 at 53', and bar 52 is connected to block 5| on which contactors 45 and 55 are mounted, rearward motion of the upper portion of spring 55 will cause contactors 45 and 55 to move rearwardly and break the circuits between 45, and 41', and between 55, 45', and 45'.

Metal retainer 25 extends rearwardly from plate through a portion 53 which is cut out of plate 55 for slidable movement therethrough of retainer 25. The portion of retainer 2B which so extends from plate 55 is telescoped by a coil spring 54, f predetermined strength. An op-` tional bellows may telescope spring 54. A cap 55 is removably mounted onto plate 55 by a bolting means (not shown) in order to house the spring 54 and the rear portion of retainer 25. To cap 55 at 51 is soldered or suitably connected a hollow coil 55 which is filled with a liquid of predetermined expansion characteristics. 'I'he end of the tube or coil 5l which is adjacent cap 55 is suitably coactive with the rear face of retainer 25 so that the expansion or contraction of the liquid in coil 55 will reflect itself upon retainer 25 and cause same to move accordingly; the other end of tube or coil 55 is suitably connected to the oven element and capable of transmitting the thermal conditions therein to the liquid within the tube or coil. The association between the coil 55 and the switch I5 through the usage of the various springs in the system together with the proper hooking up of the various circuits seems to have been clearly defined in the foregoing, but will be elaborated upon in the following.

'I'he standard 3wire domestic electric service is connected to the control unit, the 220 v. potential being connected to terminals 45 and 45, and the neutral wire of the system being connected to terminal 55. The heating element is connected to terminals 41 and 48.

Switch i5 is "ofY in all figures and, as such. all circuits are open. Cam 5|, as shown in Figs. 2 and 3, retains Bakelite plunger 32 in its rearwardmost position so that spring conductor 54 is kept from contacting screw contacter 35. The rear face of the upper portion of spring conductor 54, being in contact with the insulated support 5| (not shown) for metal contactors 45 and 55, prevents contactors 45 and 55 from contacting the rear portions 45', 45', 41' and 45' of terminals 45, 45, 41, and 45.

However, when switch |5 is turned from its "ofP position, plunger 32 is allowed to move forwardly, causing spring conductor 34 to close the circuit containing the green light 45, and causing conductors 45 and 50 to close the circuit containing the oven heating element (not shown). The contact between conductors 54 and 55 not only causes the green lamp to be illuminated but also, upon the contact between conductor 55 and terminals 45 and 45', to cause theillumlnation of the red lamp. Simultaneous illumination of the two lamps 45 and 4| shows, by lamp 45,l that the control is other than "off," and, by lamp 4|, that the oven element is in collar 21 against spring 5S relieved. Spring 50 flies forwardly at the bottom thereof and takes with it the lower portion of spring J. Forward motion of the lower portion of spring 53 causes rearward motion of the top portion thereof and obvious rearward motion of the insulating block di (not shown) upon which conductors 49 and 5G are mounted. This action breaks the circuits in which are disposed the red light and the oven eiement, and both the red light and the oven. element cease having current pass through them. it will be noted that the green light remains unaffected because of the' independence of the circuit in which same is disposed from any other circuit in the system.

lne oven, after cooling somewhat, causescontraction of the liquid in coil 88 and the pressure spring 64 is thereby relieved. This action causes the re-closing of the circuits in which the red iight and the oven element are disposed, and

the red light again goes on and the oven element is again subjected to the heating effect of the current passing therethrough.

is understood that the cooling and re-heatof an oven is intermittent during a cooking operation because oi' the opening and closing of the door therefor 'and because of other conditions surrounding the oven.. For that reason the unit comprised in the invention is delicately constructed to have reflected thereupon the slightest thermal changes. It wiilbe noted that the ability of spring 64 to resist expansion of liquid in coil -68 is proportional to the degrees which switch IS is turned'.

' les indicated by Fig. 4 which shows the control oil position the heating element is enertraced through contact 45, switch 49, contact 4l,v

contact 48, switch 5l! and contact 4,6.

` The circuit for the lamp t@ is through contact 45. bracket 43, lamp 4D, bracket 3l, bolt 38. spring switch 34, contact 35 and thence to the neutral wire 36.

The circuit for the lamp 4l indicating passage of current through the heating element is through contact 46, switch 50, contact 48, bracket 43', lamp 4l, bracket 3l, bolt 38, spring switch 34 and contact 35 and thence to the neutral wirev 38. Y It is to be understood that the invention is not to be considered as limited to the embodiments and applications thereof which have ,been selected for the purposes of illustration, but is intended, rather, to embrace and include all other embodiments and applications-of the new and useful principles thereof, which are to be considered reasonably within the scope ofthe appended claims.

We claim:

i. In a stove, a pair of switch terminals connected to a source of high potential, a pair of contacts having aneelectric heating element for the oven of said stove electrically connected thereto, a neutral line, an electric signal operatively connected to said line and to one of said terminals, a second electric signal of a dill'erent character than said first-mentioned signal operatively connected to said line and to one oi said contacts, said terminals and contacts comprising a part of a control switch. which includes a movable member operable for connecting said contacts to said terminals so as to energize said heating element and said second signal, means for actuating said movable member to open and close the circuit through said heating element and second signal, thermalresponsive means for operating said actuating means to open and close the circuit through said heating element and second signal, and manual means for operating said actuating means so as to select the temperature range in which said thermal responsive means will operate and locking said movable member against closing the circuit when the manual means is in off position, and switch means opened by such locking action included in the circuit of at least said first-mentioned signal.

2. A constructionas set forth in claim l in which the last-mentioned switch means is in cluded between the neutral line and said signals.

"fnavnaN F. DUPUIS. 

